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That's because Bill Gates DID great things for humanity. He has given over a billion dollars to humanitarian causes including organizations to help children with HIV/AIDS. Sorry guys, I'm out of the hate game. The days when I thought Bill Gates was evil are long gone.

Don't those billion dollars come with a nasty caveat, namely that the countries benefitting from the money have to agree to obey foreign patent laws and not buy much cheaper generic antiretroviral drugs made in places like India, making them dependent on his money from then on? Something like that anyway. It's not exactly charity.

You mean a rip off of CP/M. Microsoft didn't ever rip off UNIX - NT's POSIX compliance was obtained through legal means (paying to be certified). Even Apple (MacOS X based on NeXT which was built on top of BSD) wasn't POSIX compliant for a long time (they were always POSIX compatible, but they didn't pay for certification until X.3 or so).

And to the post below, Xenix was also legally licensed, but MS couldn't get a license to use the name UNIX so they created their own, which was hardly original in the 1970

Unless you were as thick as two short planks(and many sadly are), you would never ever ever ever run a nuclear plant on windows. Or even linux. Or even siemens hardware in general. You would use a robust PLC from someone like Omron and some dedicated HMIs to backup your SCADA, which will sadly run windows. The PLC program should be properly interlocked and fail safe. The plant runs on the PLC not the SCADA.

You have failed to take into account the practical reality of turning a research thorium reactor into a working commercial scale one. Demand for nuclear is falling and development will take at least a decade and tens of billions of dollars minimum, so good luck getting someone to invest in that.

Back in the 60s when it was assumed that nuclear power would be too cheap to meter people were willing to throw lots of money at the problem, but by the 70s it was clear that actually it was going to be horrendously expensive and not economically viable for private companies to do by themselves.

The design Bill Gates is proposing isn't inherently safe - it is similar to IFRs (Integral Fast Reactors) that use liquid sodium as a coolant. Liquid sodium is highly flammable when exposed to the atmosphere, and one prototype IFR reactor in Japan was shut down indefinitely due to such a leak.

Incidentally, IFRs fully burn their fuel, TWRs don't and leave some trans-uranics like another reactor variant called LFTR (liquid fluoride thorium reactor) which is self-cooled by molten salt and doesn't need another coolant, making it inherently safer. The main advantage of TWR over IFR is that it is bigger and designed to recycle its fuel and run for an extended period. One advantage of TWRs is that they can burn any actinide fuel (thorium up), including non-fissile U238, which is probably why they are favored over LFTRs - Thorium, while 4x more abundant than Uranium, is also 5000x as expensive right now because there is no market for it (incidentally, LFTRs can also be fueled by U235 and I've heard they can burn nuclear waste, but I guess that would make them LFURs...). In any case, IFRs and TWRs, unlike LFTRs, still run a risk of meltdown, so I wouldn't call them safe.

Incidentally the US nuclear regulatory commission (NRC) seems to be the stick in the cog blocking the development of IFRs and LFTRs - they both need reprocessing facilities and they fear creating a reprocessing facility on US soil will create a so-called "plutonium economy" and risk proliferation, even if the facility was built next to the plant and the materials never leave. When John Kerry (for the most part) forced the shutdown of the IFR, proliferation was the key reason, and the reality is the plutonium in the IFR would never be purified or need to leave the plant (sometimes I just want to take a baseball bat to some Senator's heads, and no, I don't pick them by party). By making a long burning IFR, they are working around the regulatory loophole holding up a potential implementation, but they still have to build the test reactors elsewhere because the NRC makes it nearly impossible (and thus China's involvement).

Between pro-business Republicans in the back pockets of the power industry that want no other reactors other than Light Water Reactors (because fuel enrichment is extremely profitable, especially when you sell the service to yourself and pass the cost on to consumers) and uninformed anti-nuclear Democrats that oppose nuclear energy entirely without even listening to any arguments for it, politically it is a dead end to try and get any design built in the US.

Unless you were as thick as two short planks(and many sadly are), you would never ever ever ever run a nuclear plant on windows. Or even linux. Or even siemens hardware in general. You would use a robust PLC from someone like Omron and some dedicated HMIs to backup your SCADA, which will sadly run windows. The PLC program should be properly interlocked and fail safe. The plant runs on the PLC not the SCADA.

There are many different systems at a huge power plant. Some of them are more critical than others.

Hence for something like the control-rods or other safety shut-down mechanisms, yea you probably want them to work even without computers. Heck, many modern plants suspend the control rods from electromagnets, meaning they will drop into the core if the power is cut.

On the other hand, the computers you use to e-mail the kitchen staff, to tell them you're out of plastic cups in the cafeteria, can probably be run on any old desktop OS.

There are several gen 3 and 4 reactors which have passive cooling system so that in the event of an emergency shutdown the temperature falls (not rises) when active cooling is lost.

Also for the most part active cooling systems are incredibly simple. Your control system has shat itself and the reactor is in shutdown? Go outside flick the auto/man switch next to the motor and hit the green button to get the cooling pumps going.

I don't know about the TWR design, but the pebble bed reactor design basically put flecks of uranium oxide inside graphite balls and use that to generate heat. That heat goes through the wall of the vessel they're contained in, heating the water, which turns the turbine. If there's a failure in a pump somewhere, you drain the primary coolant loop and leave the pebbles. There's no way the heat of the uranium could cause any sort of problem, and because there's no water anymore, you can't get an explosion.

It's worth noting that at Fukishima many of the main problems appear to have been with spent fuel rods that they just didn't have anywhere safe to store without power. Similar US plants are reputed to have the same problems.

No no no, you don't want to develop something critical like that from scratch unless you have a large team of physicists, electrical engineers, mechanical engineers, software engineers, testers, networking experts and so on, plus a spare reactor or two to use in development and destructive testing. It is much better to use a tried and proven system, or at least build your improvements on it.

The only vulnerability in the SCADA system is its ability to communicate with the outside world, so you need to use mo

Except in the US businessmen are cheap and have more interest in cutting costs than following safety rules. Fukashima had the same attitude of costs and could have avoided the meltdown. I would feel better if governments ran them rather than for profit deregulated corporations who have brainwashed the populace that anything else is evil socialism.

Why you write off as hysteria is actually just people's legitimate concerns. In a country where everything has to be earthquake and tsunami proof and yet occasionally people still get hurt or killed the pragmatic view is that accidents will happen, no matter how hard to try to prevent them. People simply do not believe that you can build a completely safe nuclear power industry where not on the reactor but all the support services like fuel refinement and waste disposal are immune to natural disaster or human error.

The question then is do we accept that risk and build new nuclear plants anyway? You can accuse people of NIMBYism but having seen what happened to people living around Fukushima I think you have to admit that the potential for having your life ruined is not something people can ignore. Of course it doesn't just affect people living near the plant, it has affected the whole country and if it had been much worse it could have reached other countries too, like Chernobyl did.

Japan is fortunate in that it has enough natural resources to replace nuclear with renewables now. It won't happen over night but then again neither will developing new metldown-proof thorium reactors. Given the choice people prefer the safe and clean option.

On top of that there is also some general anti-nuclear sentiment because of the two atomic bombs that the US dropped, but it isn't as simple as you think. North Korea almost certainly has nuclear weapons now, as does China. Japan could probably build one in a few months but doesn't because it would just escalate the situation, but some politicians have been advocating more military build-up so naturally there is opposition.

So the 20 odd years that people have been blocking to shut down the old BWR's to replace them is hysteria?

Wipe the foam away from your mouth and listen to what they are telling you. They did not block the shut down of existing reactors, in fact they wanted it. They are anti-nuclear, so obviously they want to close nuclear reactors. Are you really so stupid you can't understand that?

And yes, there are alternatives that are not nuclear or coal. Again, you seem to have missed that part.

Before you accuse people of hysteria you should at least try to understand their rather simple message.

You might find it funny, but there's been an on-going series on mainichi(read japanese, or use a translator) about the problems and screw ups over the reactors and how environmentalism is as much as fault as the government.

The problem is lack of effective regulations and oversight. Making something government owned doesn't stop that. You need the people who inspect the stuff to be independent from those who profit from it. If the government wasn't full of industry lobbyists then private run - government inspected , would probably do the job pretty well.

[quote]The problem is lack of effective regulations and oversight. [/quote]

I'm not sure I can agree with that. The problem appears to be that right now, most nuclear plants are of a very old design, and that there is so much red tape in replacing them that it endangers lives.

To use a dreaded Slashdot car analogy: Most people wouldn't feel comfortable having a car using 1960's safety technology as their daily driver. Why should people be more comfortable with something as complex as nuclear power generati

To use a dreaded Slashdot car analogy: Most people wouldn't feel comfortable having a car using 1960's safety technology as their daily driver. Why should people be more comfortable with something as complex as nuclear power generation using 1960's safety technology and design?

I should point out that the Navy used a 1950's design (the S5W) well into the 90's without accidents and with very few significant incidents. The A2W plants onboard USS Enterprise are of a similar design vintage and is equally free o

You're right, its lack of regulations and oversight. Its also a panicky and scientifically illiterate population where reporting the truth to the media sends them (the media, the population, pick one or both) into a tizzy over nothing.

You obviously haven't been to China. I will agree that Americans are extremely cheap, but that pales in comparison to their Chinese counterparts. And it's so pervasive that people at every level will be looking to cut corners, usually with the hope that a little extra money ends up in their pockets. Of course, it does depend on who you're working with, because he might come across someone who's so ambitious he's willing to spare no expense.

Then maybe we should do it hella far away from someone's backyard in a lower population density area. The amount of people who might object would be small enough that an eminent domain lawsuit would pass through pretty easily. I'm pretty sure a power plant would be one of those "greater good of the people" situations like roads that a judge wouldn't hold up too long.

Of course, when China's lack of an "irrational" fear of nuclear power causes them to screw it up just like they have with other large infrastructure projects, I expect we'll see +5 Insightful comments in the thread about that nuclear accident pointing out that it could never happen in the US because they have proper regulations.

How is it irrational? Ever heard of Fukushima? Go back and follow the timeline of events. At *every* stage of the disaster experts were reassuring the public that according well accepted nuclear community engineering standards--which the plant adhere too--the next event in the timeline wouldn't happen. It became almost comical after awhile. The news about Fukushima continues to get worse to this day.

No. It's very rational to fear nuclear power, just like it's rational to fear driving on a highway. Coal plants might spew out more radiation, but they're an extremely simple, stable, and well-known quantity. You can probably predict with a high degree of accuracy exactly how many people will die of cancer from a coal plant. But nuclear plants very clearly have many unknown and unpredictable characteristics. Nuclear engineers earned a giant *FAIL* on Fukushima.

I'm still very pro-nuclear. But after Fukushima nuclear engineers really should learn some humility, as well as nuclear fan boys.

You can probably predict with a high degree of accuracy exactly how many people will die of cancer from a coal plant. But nuclear plants very clearly have many unknown and unpredictable characteristics.

You're doing it wrong. First of all, you can get a pretty damn good estimate of the likelihood of a major nuclear incident by dividing the world-wide number of operating hours of all nuclear plants by the number of major incidents. It isn't predictability that's the problem, it's the scope of the damage that occurs when something does go wrong.

But that isn't even a problem either -- it just sounds a lot scarier. People are irrationally afraid of things that are very rare but when they occur are very bad. It's like movie plot terrorist threats: Hardly anybody is killed by terrorists, but we spend trillions of dollars trying to reduce the amount of terrorism with unnecessary wars and security theater.

Do the math. Something which is fifty times as bad but occurs ten thousand times less often is a Good Thing. (I mean honestly, go visit an abandoned coal mine once. Then tell me the damn Superfund sites they leave behind aren't each individually worse than Chernobyl.)

If you want to educate people with "facts" you should get your facts right:1. it was a 30 year old plant 1 month away from being decommissioned;

The site had 6 reactors, only the three oldest ones where planned to be decommissioned. Also switching the reactors of would not have helped the stored fuel there... so I don't get your point.2. it was hit by an unprecedented earthquake that damaged the walls of the plant -- immediately after which the plant was shut down (the fuel rods removed);

The earth quake was 450km away! So the plant was certainly not hit by a magnitude 9 "shake".3. it was then hit by an unprecedented tsunami and is close to the sea -- this knocked out the diesel power generators and flooded the plant.

Neither the tsunami nor the quake was unprecedented. Japan was hit by similar and even worth tsunamis in history often enough.

It was an extremely unlucky sequence of events -- the reactor was designed to withstand something like a magnitude 7 earthquake (and was hit with a magnitude 9 one), and survive a 7 ft tsunami (but was hit by a 10 ft one).

You know the difference between yards/meters and ft? The tsunami wave was over 14m high. Not 10 ft wich is roughly 3 yards or 3 meters.

Yes, there are now better and safer reactor designs, but they were not available 30 years ago.

How hard can it be to have some mobile power generators available and palce them at the plant in case of emergency? That has nothing to do with "reactor design". Putting the diesel engines in a water tight envirnoment is not that hard either. Or simply making a damm like wall around the plant which is high enough...

No, they should have. They only reason the plant became a risk was due to the land dropping a meter.Should they have planned for that? maybe. Lets not forget plate tectonics was a pretty new science when the plant was designed. Seriously, like 1950-60 is when it started to become a science.

Interesting note: The people who denied plate tectonics are pretty much the previous generation of the current GW deniers. People literal refused to believe it because it went against there ideology that the world is stat

of actual decommissioned nuclear power plants. If such a list exists, it would be microscopic in comparison to the list of aging plants given a rubber stamp extension on life just so the owners never have to foot the bill or more accurately not until they bailout with their golden parachutes. This may be more of a US problem, given that corporations are firmly in control of government.

except when someone develops a safer, cleaner method of boiling water that burns through most of the "pollution" (actually viable fuel) created by the last 3 generations of the technology.

just because it's not the best now, doesn't mean it can't (in fact SHOULD) be made better, if only we were allowed to learn from past mistakes, rather than running those mistakes well beyond their designed lifetimes.

Handling dangerous waste for thousands of years is a problem, but a lot of that can be taken care of by just reusing the waste in newer types of reactors. Banning nuclear technology by preventing new nuclear plants from being built just makes the problems worse, because you can't build modern reactors that reduce or eliminate the problems with the older ones. Meanwhile, the old ones are just getting older and more dangerous, but can't be replaced because it's illegal to build any new ones...

And making several square miles of land is not a very big deal unless you've got an extremely high population density like Japan. And compared to coal mining, even if standard practice was to just abandon old nuclear reactors once they ran for a couple of decades, they'd still be wasting less land.

Could you show me where the design of the reactor was the issue and not negligence on the part of the human operators or cost cutting measures on the part of the owner? Also the newer designs are designed to shutdown when power is lost on their own. As the reaction is dependent on having power, and the cooling method is passive.

Ill-rational? Oh dear. Leave science ( and written communication ) to those capable of said tasks.

There is nothing irrational about being against the most dangerous, polluting and expensive method of boiling water ever conceived.

Hear, hear.

Coal* mining and burning has to stop. It's deadly and dirty.

The fastest way of displacing coal at present is to build natural gas plants and wind turbines, so that should be our current industrial focus. Solar will play an increasingly important role as solar technology gets cheaper and more effective.

But none of these come close to nuclear in terms of safety and environmental performance. It's hard to beat the inherent power of E = mc^2. Gas emits CO2. Solar and wind rely on the mining of huge amounts of toxic materials, much of which will have to be deposited in underground storages unless we develop ways of recycling it. (Does that sound familiar?) Nuclear is both cleaner and safer because it relies on mining of small amounts of toxic material.

If we could develop a nuclear reactor that could be produced on production lines in factories and shipped out to the customers in shipping containers nuclear could not only be the cleanest and safest alternative, but also the cheapest.

Solar and wind rely on the mining of huge amounts of toxic materials, much of which will have to be deposited in underground storages unless we develop ways of recycling it.

Sand is that dangerous? Oh I get it - homeopathic toxins where the stuff with the lowest concentration is the most dangerous. I think you've wandered into the wrong place. Engineers lurk here and we're very big on the physical sciences instead of the metaphysical crystal worshipping bullshit.

Nuclear is both cleaner and safer because it relies on mining of small amounts of toxic material.

Are these people growing up in sealed boxes? Haven't you heard of a place called Iran where their concentration of radioactive material is in the news? The way it works is very large amounts of material are mined and then a very difficult and energy intensive process (including in one process such "clean" stuff as Uranium Flourides as a gas - well I suppose that would "clean" you to your bones and then dissolve the bones) which then gives you a small amount of fuel from a large amount of ore.

More to the point, this particular reactor design works on *depleted* uranium, so you're not enriching it, but you're actually using waste from the enriching process as fuel.

There is a massive amount of depleted uranium laying around that has been stockpiled since the Manhattan Project. Using it as fuel would be far more environmentally friendly than any other base-load generation, since we've already extracted it from the ground, and it's just sitting in storage.

Using what you already have is much preferable to using what you need to go get.

The US Military uses depleted uranium in weapons. They make tank projectiles from it and shoot it at 'terrorists'. When these projectiles hit something, they vaporize into thousands (millions?) of radioactive particles. There are high rates of cancer for years after in the (terrorist) towns where they have been used. It would be good to stop using it as a munition since it does kill a lot of innocent people.

China is one of the largest CO2 polluters in the world. Traveling wave reactors are known to be incredibly clean and safe. If you give the Chinese abundant safe and clean energy, this is going to really help the global warming problem.

The reason traveling wave reactors were never used, even though the technology has been know for half a century, is that they produce no waste that is useful to making nuclear weapons. That is only reason why all nuclear power nations wanted the more dangerous reactors that ran on uranium and plutonium fission.

But modernizing the safer, non-weaponizable form of nuclear power is a great way to go.

This analogy breaks down when you consider Japan Canada Sweden Germany and the many other countries that have no nuclear weapons programs but operate a large nuclear reactor fleet. This would've particularly helped Japan when the cooling was cut off at daiichi too.

It's because all the expertise was in enriched uranium reactors, and the same reason why American companies used slightly enriched uranium plants for it: it's cheaper to improve on a current process than to throw it out and start from scratch. Sure, there's diminishing returns, but why bother with something new when in the current situation where the public is afraid of anything nuclear? But when you're in a country where public opinion is less of a problem and you have a large budget surplus, you're freer to mess around.

Sweden had a nuclear weapons program (I was extremely surprised when I discovered this. I have it from some WP article, so take it for what it is, but, Sweden officially being neutral, I guess it made sense). I would imagine the other never had one, though. But, as a sibling post pointed out, the expertise was already built up on the kinds of plants that could be used for making bombs, so building them was much easier.

China is one of the largest CO2 polluters in the world. Traveling wave reactors are known to be incredibly clean and safe. If you give the Chinese abundant safe and clean energy, this is going to really help the global warming problem.

Traveling wave reactors aren't known to be anything. No one has built one.

While I agree with everything else, I am not sure, why everyone has always to mention absolute numbers to China's CO2 production. China ist also the most populous county in the world. And the its CO2 emission per capita for 2008 is on par with Sweden or Israel and less than third of the US one (http://en.wikipedia.org/wiki/List_of_countries_by_carbon_dioxide_emissions_per_capita).

Unless one argues that the Chinese people are less valuable than the US citizens (you can't even tell them from one another!), I don't see, how one can critisise China without being a hypocrite. That goes not only to the US, Germany, France and half of the developed world in worse in that regard.

Of course, if China was to provide an equal living standard to every citizen, the situation would be entirely different. And you can surely use some metric like CO2-emission/GDP, where China would look quite terrible and make a valid argument about their efficiency. But right now, China as a whole is more CO2-free than most of the developed countries.

The per-capita stats you link to are physically meaningless (they're politically motivated statistics). What counts in terms of
environmental impact is the total output, so you should be linking to
this [wikipedia.org] instead.

For those who don't want to click the link, China, the US, and EU are the top 3 polluters, unsurprisingly.

No, individual people don't have a say in energy policies, countries do. That's why countries are meaningful in this case. To be more exact, regions with common industrial energy policies and closely related plant designs would be what matters, but countries are a good approximation. You'll note I mentioned China, the US and the EU, not the individual countries of Europe. I suppose I should have combined the US and Canada probably due to the close economic dependency between the two countries.

Unless one argues that the Chinese people are less valuable than the US citizens (you can't even tell them from one another!), I don't see, how one can critisise China without being a hypocrite.

The problem is that China doesn't even care about its own citizens, and isn't really using the industrial output it gets from the fossil fuels to improve their situation much. Shanghai is now so polluted the smog can make you not see the sun. They got mercury all over the place, and they are also one of the countries

There's another reason they don't get used. The 'standard' reactors require enriched fuels. The same companies that sell the reactors also supply the fuels, or the enrichment services. It's basically vendor lock-in.

Plutonium production for weapons is better done in a special-purpose reactor than in a power plant. Power plants need to keep fuel in place for long periods for economic reasons, which eventually produces plutonium isotopes that are undesirable for bombs.

In fact, I can't think of a single example of someone building a bomb with plutonium from a power plant.

Partially false. It's true that using a nuclear reactor to create weapons grade plutonium is not the most economic way to do it, but you're ignoring the other niceties such as the power they generate when they are not being used to create it.

The fact is any type of reactor where the fuel is easily removable can and HAS been used to create weapons grade plutonium. The only difference between weapons grade plutonium and the left over crap when the reactor runs out of fuel is the length the fuel has been in place inside the reactor. Most heavy water reactors and breeder reactors make it trivial to swap out the fuel at any point including the critical period where weapons grade plutonium is being made.

This is the reason why the world is taking such interest in Tehran's heavy water reactors.

And there were Specific [wikipedia.org] reactors [wikipedia.org] designed to create weapons grade plutonium by making extra easy to swap out fuel online, the most famous being Sellafield [wikipedia.org]. Some of these designs are still in service [wikipedia.org], though I'm unsure if those specific plants were ever used for production of weapons grade plutonium.

The design appears safe, but the same accounts for the pebble bed reactor. The trial reactor built in Germany left them with very serious radioactive pollution.

The idea of a TWR is seriously interesting of course, as it uses so much of the fuel, and leaves relatively little waste. And I think it definitely warrants more research. I understand that small-scale experiments have been done with this tech, so it seems time to try to scale it up a bit. If successful it could go a long way in solving our energy problems.

I am a strong believer in nuclear technology, but the main issue I have with it is the waste, which is so hard to handle and at the moment is basically useless, as in we don't have a way to continue using it.

Actually about the waste issue: the spent rods are known to produce a lot of heat, and need active cooling. That's at least part of the problem faced in Japan. Can't all that energy be used, one way or another?

Or is water contaminated by radioactive isotopes that's spilling all over the fucking place (see: Fukushima - no link necessary). Have you got a reactor design that economically burns cesium-contaminated water?

Putting your ridiculous statement about radioactive waste aside, I'd be willing to bet that the localized temperature inconsistencies that were seen in the AVR would likely be a problem with a TWR. Real physical systems are far different (read: more

China will use it to build and charge batteries that will be sold in Wal-Marts in the US, so this is a win-win, right . . . ? An the "traveling nuclear waves" stay in China . . . ? Isn't a traveling nuclear wave called a tsunami, and caused a disaster in Japan . . . ?

Actually the title sounds like fear mongering (Bill/China/Nukes) or a bad joke:

"So, Bill Gates walks into a bar in China with a traveling nuclear wave reactor, and the bartender says . . .

They can't help leaving behind fission products (that's where they get their energy from), which isn't too much of a problem, as it takes only about 300 years for them to decay to levels of radiotoxicity of natural uranium in equilibrium with its decay products.They will leave behind some Uranium, but this can still be used in other reactors.

The problem is mainly residual Plutonium, Americium and other elements, with half-lives of several thousand or tens of thousands of years, which require hundreds of thousands of years to decay to such levels. (Because of the very damaging high energy alpha decay, rather than lower energy and much less damaging beta and gamma decays.)

On the one hand non-fissle transuranic elements capture neutrons and interfere with the chain reaction, on the other hand capturing neutrons either splits them or eventually transmutes them into fissle elements. This turns them into fission products, which we can handle with reasonable confidence. The question now is: does the travelling wave in the travelling wave reactor provide enough neutrons to transmute and split the transuranic elements it breeds, such that the reactor as a whole reaches a stable equilibrium before the end of its operating time? Conventional reactors don't, because the chain reaction is stopped for lack of neutrons long before a stable equilibrium is achieved. Most breeder reactors do, but it depends a lot on how tight the neutron economy of the particular reactor is. And afaik (correct me if you know better or have access to specifications), the neutron economy of the travelling wave reactor is rather tight and might well be possible, that the wave leaves ever more transuranics in its wake as it moves, without ever reaching an equilibrium over the whole of the reactor.

Why is reaching a stable equilibrium before the end of operation enough? In this case you can add some additional transuranics at the start of operation and still reach the same equilibrium at the end of operation. If the amount you can add at the start (and still reach equilibrium) is larger than the amount left at the end of operation, you effectively reduced the total amount. Given that, you effectively solved the long-term problem of transuranic waste, by limiting its amount and eventually burning it.

The question is, can the travelling wave reactor do that or not? (There are other options ex post, but it is always best to not let the problem exist in the first place rather than dealing with it later.)

See technology review article [technologyreview.com]. They are "only discussions". There is no partnership and no plans to build anything. Yet. Plus the type of reactor mentioned is still just a design [technologyreview.com].

In the new design, the reactions all take place near the reactor's center instead of starting at one end and moving to the other. To start, uranium 235 fuel rods are arranged in the center of the reactor. Surrounding these rods are ones made up of uranium 238. As the nuclear reactions proceed, the uranium 238 rods closest to the core are the first to be converted into plutonium, which is then used up in fission reactions that produce yet more plutonium in nearby fuel rods. As the innermost fuel rods are used up, they're taken out of the center using a remote-controlled mechanical device and moved to the periphery of the reactor. The remaining uranium 238 rods—including those that were close enough to the center that some of the uranium has been converted to plutonium—are then shuffled toward the center to take the place of the spent fuel.

Currently there is no known material that could be used to encase the fuel rods in -- they need to survive radiation exposure for decades without expanding.

The travelling wave reactor concept appears to be basically a sodium cooled reactor that has a lot of extra U-238 , allowing it to go very long without refuelling as the enriched portion of the core "travels" along the U-238 ( this image explains the concept: http://evworld.com/press/IV_twr_concept.jpg [evworld.com] ).

I have to say I am sceptical. The main economic issue with sodium cooled fast breeders is that they are very capital intensive due to the challenges of handling flammable sodium. Thus trading even more capital investment ( in the form of a larger core ) for less frequent refuelling seems like a bad idea. Furthermore, any design that is to see widespread deployment should make use of economics of scale. Fuel fabrication, reprocessing and so on can be centralised, with a few facilities potentially serving many reactors, or even multiple nations. It thus makes little sense to move capital costs towards the power plant and reactor, away from facilities that can be centralised. This is why I doubt all the talk about "Integral" facilities or on-line reprocessing ( as suggested for molten salt reactors ).

It's not very hard to build a breeder with a 2-3 year core lifetime anyway, and you probably don't want to run it much longer than that without shutting it down for servicing, repairs, inspection and so on.

Don't get me wrong. It's a cool idea technologically. I just don't think it will be economically competitive with other Gen-IV designs. The focus for breeders today should be on reducing capital up-front investment, improved safety and reliability. No utility is going to invest billions up-front in an experimental design that is unlikely to be economically competitive with other alternatives.

Wrong. There are many, many problems with thorium.To begin with, this substance is more chemically and radiologically toxic than Pu. So having it molten 24/365 inside corroding tubes is pure suicide for a whole land.

Do you guys just make this stuff up as you go along? The half life of natural Thorium is 1.405×10^10 years. Radioactivity is the inverse of half life. (By contrast, the half life of Pu-239 is ~24,000 years, and the Iodine-125 they inject you with when you get an MRI has a half life of 59 days.)

Thorium itself is not a nuclear fuel, it's what is called a fertile material. When bombarded with neutrons it produces Uranium-233 , which is an excellent nuclear fuel, and most certainly usable in a nuclear weapon. The process is very similar to how Plutonium-239 can be made by bombarding Uranium-238 with neutrons.

The main reason people don't use Thorium and U-233 for making bombs is that the U-233 tends to become contaminated with highly radioactive isotopes, making it difficult to handle. In principle you can avoid this by using a more elaborate irradiation and separation technique, but it's just easier to use Uranium-bred Plutonium instead.

To summarise:Thorium-232 and Uranium-238 are not on their own useful for nuclear fuel or weapons. However, they can be turned into fissile material by bombarding them with neutrons.

In this way Th-232 can be turned into U-233Whereas U-238 can be turned into Pu-239.

Both U-233 and Pu-239 can be used for weapons, but it is easier to keep the radioactivity of the Pu-239 low.Hence it is easier ( and cheaper ), to use Uranium fuelled reactors to make a bomb than to use Thorium.

Suicide is not a coward's way out. Yes, it passes the buck, but what needs to happen in someone's head which allows them to go against every instinct every living thing has had for billions of years - survival - has to be pretty god-damned tough to go through.

This sort of tech has been pushed and rejected by most of the western world due to fear mongering and morons that can only think of japan or chernobyl when they hear the phrase nuclear power. Sadly China get a jump to clean and safe energy because the rest of the world panda to the irrational morons in society, on the whole though at least this reduces the worlds Coal burning.